Leopold Ružicka was in many ways a remarkable person - be it his excellence in organic chemistry, his unique presentation style, his fight for better education, or his interest in art collection, which he manifested via the funding of the Ružicka foundation.His scientific achievements include the first-time synthesis of the hormones androsterone and testosterone (for which, amongst other things, he received one of the 1939 Nobel Prizes in Chemistry) as well as the first-ever structural elucidation of lanosterol, which represents the base compound that all steroids (e.g. cholesterol and the male and female sex hormones) are biosynthetically derived from. For many years, Ružicka’s laboratory at the ETH Zürich was the prime research location for organic chemistry in the world.

His work strongly influenced Nobel Laureates such as Konrad Bloch and Feodor Lynen (1964 Nobel Prize in Physiology or Medicine for the elucidation of cholesterol and fatty acid metabolism), Robert Woodward (1965 Nobel Prize in Chemistry) or Derek Barton (1969 Nobel Prize in Chemistry). With Barton, Ružicka competed for the structural elucidation of lanosterol and won. Vladimir Prelog, who was awarded one of the 1975 Nobel Prizes in Chemistry, was Ružicka’s student.

In the present lecture, Ružicka gives a review of his work, starting from a “reckless” claim he made at a conference in 1923. Back then, he had predicted that bile acids are biosynthesized from cholesterol and not from fatty acids, as postulated by 1927 Nobel Laureate Heinrich Wieland at the same conference. Ružicka further claimed that cholesterol is made from triterpenes. It took him and others several decades to deliver the proof for these hypotheses, but of course, Ružicka was right. Here, he discusses the experiments that led to this insight, following the entire biosynthetic route from carbon dioxide to cholesterol.

A clearly audible passion for his subject and a fine sense of irony make the talk a pleasure to listen to. They are exemplified in many classic quotes such as: